Method of treating lead dross



Sept. 13, 1927.

1,642,358 0. P. CHISHOLM METHOD OF TREATING LEAD DROSS 7 Filed April 17. 1926 5cm}: Iron or Lead BIO$+ Furnace Speiss .Sln'mmings which comprises an infima+e mixfure ofdross and flux.

Revrbemfory Furnace Slag Copper Mafia 5Eeis5 Lead l/WE/VTO mm 7 AM A TTOl-P/VE Y Patented Sept. 13, 1927.

UNITED STATES PATENT OFFICE.

0mm PERRY CHIBHOLI, OI DUBANGO, COLOIfIADO, ABSIGNOB TO AMERICAN SHELT- ING AND DEFINING COIPANY, OF NEW YORK, N. Y -A CORPORATION OF NEW JERSEY.

METHOD OF TREATING LEAD DBOSS.

Application fled April 17, 1928. Serial No. 102,633.

This invention relates to a process for refining lead dross which 1s produced in treating impure lead, and relates particularly to the separation of copper, arsenic and other impurities from the lead in the form of a speiss. M a

Lead ores frequently contain substantial amounts of copper, arsenic, iron and other metals, which are reduced when the ores are smelted and which are tapped from the furnace with the lead. It is customary to smelt lead ores in a' blast furnace, and the slag and speiss are first taped from the furnace into one or more sett ers to separate them from. the lead bullion.

The lead bullion may be placed in drossing Kettles and the dress: may be skimmed from the top thereof an subjectedto further treatment to separate and recover the lead and the other metals. contained therein.

According to my improved rocess the impure lead dross is mixed wit fluxes in proper amount and under suitable conditions to produce a speiss containin lead, copper, arsenic, iron and other metas, and also a liquid sla which; may carry W1tll it some matte. he speiss has a relatively low iron content, owing to the excess of the fluxes, but his relatively high in lead. Also, owing to the excess of film and to the absence oi an excess of sulphur, comparatively little niatte is formed. --The slag is first tapped 03 leaving the speiss which normally forms a layer on the topof the lead bath. Thereafter. the iron is addedto the bath in proper quantity to replace the lead in the speiss, whereby a speissis formed that is high in copper but low in lead. Preferably the fluxes such as silica and limerock are added to the drossing kettles in uantities suficient to cause a portion of t e fluxes to form an intimate mixture with the dross and to unite with the iron to form a slag in the subsequent treatment. The dross mixture with free fluxes is. skimmed from the kettles and is charged preferably into a rein amounts suflicient to insure removal of practically all of the copper and arsenic rom the lead without substantial loss of lead. The lead previously combined with speiss that may have been formed is replaced to a large extent by the iron. The treatment is continued approximately at smelting temperatures for a period of time depending on the character of the bath which will permit segregation of the copper and the arsenic as a speiss and which will also permit the removal of the layer of speiss without the removal of any substantial amount of lead.

The invention further consists in the new and novel features of operation and the new and original arrangements and combinations of steps in the process hereinafter described and more particularly set forth in the claims.

The accompanying drawing shows a flow diagram illustrating the various steps in the practice of my improved process.

The lead ore, which may contain copper,

iron, arsenic and other minerals, is smelted in a lead blast furnace of the usual type. The impure lead is tapped from time to time in the usual manner in the one or more settlers adjacent the blast furnace. These settlers permit segregation of some of the impurities which may be 1n the form of an iron speiss floating on the top of the molten bath and which may be skimmed oil to be used in subsequent treatment as hereinafter described. The lead with the remaining impurities is then conducted to a drossing kettle where crushed silica and limerock are added in proportions de ending u on the composition of the lead ullion. 0 lead is dross ed in the usual manner, and the skmmmings, which contain the copper, arsenic and other impurities, together with free silica and lime, is removed. It is the treatment of this dross from the drossing kettles which is the primary object of this invention, although 1t will be understood that'the process is applicable to the treatment of any kind of impure lead and also of other metals which contain arsenic and copper that can be caused to combine as a speiss.

- The dross is char ed into a reverberatory furnace which may of standard ty e and fired with coal or oil, as desired. refer- Inn ' in copper.

ably about twenty to twenty-five tons of the dross is charged into the furnace during each eight hour shift.

The furnace is maintained at a normal operating temperature range of approximately 2100 to 2400 degrees Fahrenheit, so that the charge melts down rapidly. A liquid slag and very little matte is formed together with a speiss which is relatively high in lead, copper and arsenic but low in iron.

The sla is then skimmed off, and scrap iron is a (led in desired quantities. The iron is melted down completely without the addition of any fresh charge of dross, and the bath is subjected to the smelting temperature until the speiss forms as a layer on top of the molten lead. Meanwhile lead can be tapped from the furnace from time to time through a siphon lead'well, but the speiss is allowed to accumulate and is tapped off when the layer .is of sufiicient thickness or at suitable intervals, dependin on the size of the furnace and the operatmg conditions. The iron replaces the lead and produces a speiss that is relatively high For example, the speiss may contain approximately per cent copper, 15 per cent iron, 12 per cent arsenic and onl 10 per cent lead. The resulting lead bu 'on is comparatively low in arsenic and copper content.

11 place of scra iron, blast furnace speiss may be introduce into the bath. This material is recovered from the settlers through which the slag passes prior to its discharge and is relatively high in iron while low in copper, since the copper is tap ed out with the lead. If iron speiss is su stituted for scrap iron it may be added in weighed amounts when the furnace is charged with the dross, and the dross and blast furnace speiss smelt down together.

Any matte which ma be formed owing to the presence of sulp ur in the dross is carried oil by the slag, which may be tapped into kettles, and thereafter the matte is re covered when the slag is broken up.

means of this process practically all B of the lead contained in the dresses from blast furnaces and settlers and drossing kettles may be recovered in a relatively pure condition by separating therefrom the copper, arsenic and iron as a coppenspeiss in a single operation which may be carried on in a reverberatory furnace permitting maximum economy in operation. By completely removing these impurities from thebullion, subsequent refinin operations are materiall y simplified an the expense of refining the lead is correspondingly reduced. The copper s i'ss whic results from the operation of t e rocess may be treated by standard metho s to recover the copper and other contents having a commercial value.

Although I have shown and described and have pointed out in the annexed claims certain novel features-of the, invention, it will be understood that various omissions, substitutions and changes in the several steps of the process and in its operation may be made-by those skilled in the art without de arting from the spirit of the invention.

aving described my invention, 1 claim:

1. The process of treating impure lead dross to remove copper as a speiss,which consists in mixing the-dross with fluxes and subjecting the same to a smelting temperature to promote the formation of a speiss containing copper and lead, and then replacing the lead with iron in said speiss without replacing the copper.

2. The process of treating impure lead dross to remove copper as a speiss, which consists in mixing the dross with fluxes and subjecting the same to a smelting temperature to promote the formation of a speiss containing copper and lead, and then replacing the lead in said speiss without replacing the copper.

3. Process of treating lead having copper, arsemc and other impur ties therein, comprising smelting said lead to produce copper speiss, controlling the lead content of said speiss by use of a reagent and con trolling the amount of said reagent in said copper speiss to cause said speiss to have a high copper content and a low lead content.

4. Process of treating lead having copper, arsenic and other impurities therein, comprising smelting said. lead to produce copper speiss, controlling the lead content of said speiss by the use of iron and controlling the iron content of said speiss by adding fluxes.

5. Process of refining lead dross containing copper, arsenic, iron and other impurities, which consists in mixing the dross with fluxes adapted to form a liquid slag, smelting said dross and fluxes and permitting the formation of a speiss cpntaining copper and lead, and adding iron in proper amounts at an appropriate term eratnre to replace a substantial portion 0 the lead in said speiss.

6. Procem-of refining lead dross containing copper and other impurities adapted to form a speiss, which .consim in smelting said dross with fluxes at an appropriate temperature to form a liquid slag and a speiss containing lead and co per, and adding a reagent to the molten ath to reduce the amount of lead in said speiss.

7. Process of handling copper from lead blast furnaces used for smelting lead ores containing copper, iron, arsenic and other impurities, comprising mixing a flux of crushed silica and limerock in a dressing kettle with lead bullion from the leadjblast furnace, drossing and skimming the lead by suitable reagents, feeding the resultant from said furnace ina copper speiss skimmings of flux and drostoareverberatory furnace, introducing lead blast furnace speiss with the charge intosaid reverberatory furnace, allowing the charge to melt I down to produce copper speiss, tapping said reverberatory furnace to draw off the copper speiss, and recovering the copper from said copper speiss. a,

8. Process of handling copper from lead blast furnace used for smeltmg' lead ores containing copper, arsenic and other impurities, comprising placing lead bullion from said.- furnace .in a drossing kettle, drossing and skimming the lead in said kettle, feeding the resultant skimmings to a reverberatory furnace to produce copper speiss controlling the lead content and speiss by the use of iron, .controlling the iron content of said speiss by, adding a flux, tapping said reverberatory furnace to draw of the copper speiss, and-recovering the copper from the copper speiss.

9. Process of handling copper from lead blast furnaces used forsmelting lead ores containing copper, arsenic and other impurities, comprising placin lead bullion rossing kettle, drossing andskimming the lead in said kettle, feeding the resultant skimmings to a reverberatory furnace to produce copper speiss, controlling the lead content .of the by use of a reagent, controlling the amount of said reagent in said high in copper content from lead speiss, tap ing said reverberato furnace to draw 0 Y the copper speiss, an recovering the copper from the copper speiss.

10. Process of separating copper from lead dross containing copper, arsenic and other impurities which com rises mixing the dross with aflux of silica and lime-.

'duce the lead content thereof, and subsequently removing the speiss from the molten mass. l

12. The process of recovering lead and copper from lead dross which comprises smelting the dross in the presence of a suitable flux, removing iron and sulphur as a slag, removing iron, copper and sul hur as a matte, adding-iron to displace lea in the remaining speiss, removing recovering copper therefrom.-

In testimony whereof I have hereunto set my hand. I

OLIVER PERRY CHISHOLM.

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